Monday, July 28, 2008

The statement made by climatologists that always tweaks me, and not in a good way, is the one to the effect of: “This (fill in the blank) is consistent with climate models.” This mantra is repeated in most, if not all, news articles on the current bout of Arctic warming. What the climatologists or authors of the articles fail to acknowledge is that polar amplification is part of the warming process. If the globe warms, mid latitudes of the Northern Hemisphere warm more than the tropics, and the Arctic warms more than the mid latitudes. They also fail to acknowledge that there are multiple climate forcings, anthropogenic and natural, that cause polar amplification in the ethereal world of GCMs and in the real world. These include increases in CO2, increases in total solar irradiance (TSI), El Ninos, and, contrary to usual the usual line of thought, explosive volcanic eruptions.

There are many other contributors to Arctic temperature anomalies, but for now, let’s limit this discussion to the following, since it illustrates the cause of the recent high Arctic temperatures without muddying this thread with forcings that have poorly established and documented data sets.

A DEFINITION OF POLAR AMPLIFICATION

From Wikipedia: “Polar amplification is defined by International Arctic Science Committee on page 23 of the Arctic Climate Impact Assessment ‘Polar amplification (greater temperature increases in the Arctic compared to the earth as a whole) is a result of the collective effect of these feedbacks and other processes.’ It does not apply to the Antarctic because the Southern Ocean acts as a heat sink. It is common to see it stated that ‘Climate models generally predict amplified warming in polar regions’, e.g. Doran et al. However, climate models predict amplified warming for the Arctic but only modest warming for Antarctica.”

A DISCUSSION ON TROPICAL TROPSHERIC TRENDS AT REALCLIMATE

How does this relate to Arctic warming and polar amplification? Read on.

Gavin Schmidt of GISS: “Whether the warming is from greenhouse gases, El Nino's, or solar forcing, trends aloft are enhanced. For instance, the GISS model equilibrium runs with 2xCO2 or a 2% increase in solar forcing both show a maximum around 20N to 20S around 300mb (10 km):”#I’ve added the two illustrations from the RealClimate thread as Figures 1 and 2. Figure 1 shows the tropical enhancement and polar amplification for a doubling of CO2 and Figure 2 illustrates the same effects for a 2% increase in solar irradiance.#

Gavin Schmidt continues: “The first thing to note about the two pictures is how similar they are. They both have the same enhancement in the tropics and similar amplification in the Arctic. They differ most clearly in the stratosphere (the part above 100mb) where CO2 causes cooling while solar causes warming. It's important to note however, that these are long-term equilibrium results and therefore don't tell you anything about the signal-to-noise ratio for any particular time period or with any particular forcings.

“If the pictures are very similar despite the different forcings that implies that the pattern really has nothing to do with greenhouse gas changes, but is a more fundamental response to warming (however caused). Indeed, there is a clear physical reason why this is the case - the increase in water vapour as surface air temperature rises causes a change in the moist-adiabatic lapse rate (the decrease of temperature with height) such that the surface to mid-tropospheric gradient decreases with increasing temperature (i.e. it warms faster aloft). This is something seen in many observations and over many timescales, and is not something unique to climate models.”#There, I wasn’t making this up. To rewrite the pertinent point in the above RealClimate quote: The pattern (the same enhancement in the tropics and similar amplification in the Arctic) really has nothing to do with greenhouse gas changes, but is a more fundamental response to warming (however caused). He couldn’t have been more forthcoming than that. In the first of the quoted paragraphs, he also inferred an El Nino has the same impact on the Arctic as a 2% increase in solar forcing and a doubling of CO2.

In it, on page 204, under the subheading of “5.3. Stratospheric Heating”, Alan Robock explains the impact explosive volcanoes have on winters in years after an eruption: “After the 1982 El Chichon and 1991 Pinatubo eruptions the tropical bands (30S–30N) warmed more than the 30N–90N band…producing an enhanced pole-to-equator temperature gradient. The resulting stronger polar vortex produces the tropospheric winter warming...”

In Chapter 2 of AR4, (page 195), the IPCC describes this winter warming further: “Anomalies in the volcanic-aerosol induced global radiative heating distribution can force significant changes in atmospheric circulation, for example, perturbing the equator-to-pole heating gradient…and forcing a positive phase of the Arctic Oscillation that in turn causes a counterintuitive boreal winter warming at middle and high latitudes over Eurasia and North America…”

Volcanic eruptions create short-term anomalies in Arctic temperature.

ARCTIC OSCILLATION

This link to a discussion on the Arctic Oscillation (AO) is being provided for reference purposes, but will not enter into the following discussion. JISOA does a great job of defining and documenting the effects of the AO at a basic level. No reason for me to repeat it. Refer to:http://www.jisao.washington.edu/ao/

ILLUSTRATIONS OF POLAR AMPLIFICATION

The typical alarmist view of Arctic temperature is illustrated in Figure 3, which is a graph of Arctic and Global temperature anomalies from January 1975 to March 2008. Both signals are smoothed with an 84-month filter.

Figure 4 illustrates the same Arctic and Global Combined surface temperature anomalies, but in this graph the time scale is expanded to almost 130 years, from January 1880 to March 2008. From 1920 until the early 1940s, Arctic temperatures more than doubled the rise in global temperature. Arctic and global temperatures decreased from the mid-40s till the early seventies. Then Arctic temperatures began to rise and global temperatures soon follow. The Arctic rise again doubles the pace of the globe from the mid-1970s to present.http://i34.tinypic.com/16h2x4.jpgFigure 4

Subtracting global temperature anomaly from the Arctic anomaly creates to a graph that reinforces the opinion that the present Arctic warming is unprecedented. Refer to Figure 5. The current residual Arctic anomaly is much higher than the peak of the 1940s. The same data unfiltered, Figure 6, doesn’t help illustrate the cause of the recent bout of high Arctic temperatures.http://i37.tinypic.com/2lrxtu.jpgFigure 5

Using the MSU data from UAH clarifies matters. In Figure 7, Global, Northern Hemisphere, and Arctic temperature anomalies from December 1978 to April 2008 are shown. The data has been smoothed with a 5-month running-average filter. The graph is a wonderful illustration of polar amplification. Note how, prior to 1978, Arctic temperatures reacts to perturbations at an amplified rate, but it follows Northern Hemisphere and Global temperature anomalies. Then, after the 97/98 El Nino, there is a step change in Arctic temperature that shifts it more than 0.5 degrees C.http://i34.tinypic.com/2cxasl3.jpgFigure 7

Did TSI or CO2 rise significantly between the late 90s and now? No. That appears to leave only one climate forcing capable of creating the sudden rise in Arctic temperature: the 97/98 El Nino.

Saturday, July 26, 2008

Figure 1 is a simplistic illustration of ocean gyres. In the following, I’ve illustrated SST anomalies at the “centers” of all five. It appears that SSTs at the center of the North Atlantic gyre lead SSTs for the majority of the North Atlantic by almost three years. Could SSTs at the center of the North Atlantic gyre be used to predict the temperature of the North Atlantic and its impacts on European and North American climate?

Figure 2 depicts the locations of the data sets used in the following. I did NOT perform a detailed analysis of ocean currents to pick the spots; I eyeballed centers based on the representations of the gyres in Figure 1. I’m a blogger, not a climatologist; that’s my excuse. The following are the coordinates used:North Pacific Gyre = 15 to 25N, 150 to 160WSouth Pacific Gyre = 45 to 55S, 135 to 145WNorth Atlantic Gyre = 30 to 40N, 35 to 45WSouth Atlantic Gyre = 35 to 45S, 15 to 25WIndian Ocean Gyre = 32 to 42S, 80 to 90Ehttp://i37.tinypic.com/kd90du.jpgFigure 2

All five data sets are shown in Figure 3, which clearly illustrates that there are no obvious relationships between the SST anomalies of the group as a whole.http://i35.tinypic.com/29m1t21.jpgFigure 3

The SST anomalies of the North and South Pacific gyres are illustrated in Figure 4. The mutual influences are obvious, as are the greater variations in the North Pacific signal. Note that both filtered signals are decreasing before, during, and after the 97/98 El Nino.http://i33.tinypic.com/r8e1eg.jpgFigure 4

In Figure 5, the SST anomalies for the North and South Atlantic gyres are presented. At first glance, it almost appears as if the South Atlantic, with additional underlying oscillations, lags the North by around 40 years. However, a closer inspection reveals that the South Atlantic has an SST anomaly rise from the 1960s to the early 1980s, then a drop from 1990 to present, reminiscent of the Southern Ocean SST anomaly curve. This is later compared in Figure 8.http://i35.tinypic.com/351tksi.jpgFigure 5

The SST anomalies at the centers Northern Hemisphere gyres are shown in Figure 6. Recall that these data sets may not be representative of the oceans or their climatic effects. They are not from scientifically selected areas and may or may not be at the centers of the gyres based on ocean currents. Regardless, the Atlantic signal has a higher amplitude than the Pacific, with less noise.http://i34.tinypic.com/20ftd90.jpgFigure 6

Figure 7 shows the SST anomalies at the centers of the three Southern Hemisphere gyres. The South Pacific curve is much flatter than the two others, while the shapes of the South Atlantic and South Indian Ocean data sets agree with the overall shape of the Southern Ocean SST anomaly curve, Figure 8.http://i34.tinypic.com/2mniqt5.jpgFigure 7

Of the SST anomaly data sets illustrated, the North Atlantic gyre signal has the strongest oscillation, with the least noise. In an effort to determine how widespread that THC/MOC signal is, I used the original coordinates of the center of the North Atlantic gyre as a starting point, then expanded the area in 10 degree steps of latitude and longitude. Refer to Figure 9.http://i35.tinypic.com/33ej7kk.jpgFigure 9

As could be expected, the smaller area had the greatest variation. Refer to Figure 10. What was unexpected was how little the variance was between the smallest and largest areas. The final point that stood out was the time lag between the smallest and the largest areas. Could this lag be present in a comparison of the center of the North Atlantic gyre and the North Atlantic SST anomalies?http://i37.tinypic.com/2l7upc.jpgFigure 10

Figure 11 illustrates the two areas bordered by the Black and the Bronze rectangles used in the following comparison. Disregard the other intermediate areas depicted; their curves simply cluttered the graph.http://i38.tinypic.com/157ghs2.jpgFigure 11

Figure 12 shows the SST anomalies for the center of the North Atlantic gyre (30 to 40N and 35 to 45W) and the North Atlantic (0 to 65N and 0 to 80W) from 1854 to 2008, smoothed with an 85-month filter. Note how the major changes in trend of the curve for the Center of the North Atlantic gyre occur about 3 years before the curve for the majority of the North Atlantic.http://i35.tinypic.com/o6a0bk.jpgFigure 12

Amazingly, when the time span is shortened to the last 30 years, and when one data set is shifted 35 months, the two curves correlate very well. Refer to Figure 13, in which the data has not been smoothed. This seems to indicate that the SST anomaly at the center of the North Atlantic gyre could be used to predict trends in North Atlantic SST.http://i34.tinypic.com/oatb7p.jpgFigure 13

Documenting the THC/MOC curve in the North Pacific and this discovery have made all the work that went into creating this series on the Smith and Reynolds SST data worthwhile.

This post, the second and last of the series, will cover those ocean areas that the third cell of IPCC TAR Figure 2.9 shows as having warmed from 1946 to 1975. Refer to Figure 1.http://i38.tinypic.com/17wmco.jpgFigure 1

THE SST AND SST ANOMALIES OF SEVEN OCEAN AREAS THAT WARMED FROM 1946 TO 1975

For those interested in the SSTs for those areas, I’ve prepared Figure 3. The Equatorial Indian Ocean (Area B) and the Pacific Warm Pool (Area C) are warmest, and the Central South Pacific (Area D) is coolest.http://i35.tinypic.com/155p6it.jpgFigure 3

Figure 4 is a colorful spaghetti graph of the areas that warmed from 1946 to 1975 according to the IPCC illustration. It covers the period of January 1854 to May 2008. I provided the two vertical black lines to ballpark 1946 and 1975.http://i38.tinypic.com/3179zef.jpgFigure 4

In Figure 5, the Equatorial Indian Ocean (Area B) and the Pacific Warm Pool (Area C) SST anomalies are shown from January 1854 to May 2008. Those tropical areas did in fact warm from 1946 to 1975. However, what the IPCC fails to note is that the SST for those areas dropped considerably from the late 19th century to the early 20th.http://i38.tinypic.com/2s12537.jpgFigure 5

Figure 7 shows the SST anomalies from January 1854 to May 2008 for the South Atlantic (Area E) and the South Indian Oceans (Area F). Like the others, both exhibited warming from 1946 to 1975. The sudden rise from 1930 to 1940, then fall from 1940 to 1950, is a curiosity inherent in both oceans. The signals from those two areas are well correlated from 1930 to present, but prior to that time, they diverge.http://i37.tinypic.com/140m63d.jpgFigure 7

The final graph, Figure 8, illustrates the SST anomalies from January 1854 to May 2008 for the North Pacific area included in this post. While it does show that the temperature actually cooled from 1946 to 1975, the trend, not illustrated, is actually positive, due to the large drop in SST from 1946 to 1955.http://i34.tinypic.com/11glshy.jpgFigure 8

Thursday, July 24, 2008

Figure 2 illustrates the Southern Ocean SST anomalies from January 1854 to May 2005. The data is raw and smoothed with a 37-month filter. Using the smoothed data as reference, the significant rise in SST from the mid-1960s to the early 1970s is unusual, especially since it’s followed by the precipitous drop that begins January 1997, a few months before the start of the El Nino of the century.http://i38.tinypic.com/ddesko.jpgFigure 2

In Figure 3, the time span has been shortened to 30+ years. It’s interesting to note that even though the trend was negative, the late 1990s rise in SST occurred before the 97/98 El Nino and that the later spike happened in September 1999, almost a year and a half after the peak of that El Nino. A Rossby wave maybe?http://i38.tinypic.com/2n6rwon.jpgFigure 3

The SST anomalies of the Southern Ocean segments are then illustrated in Figure 7. The areas are identified by the letters in the legend and the map. All of the curves display a significant drop in SST in recent years. The two unusual curves are those that are east and west of the Antarctic Peninsula, curves A (blue) and B (red).http://i34.tinypic.com/2jg9lb9.jpgFigure 7

Figure 8 illustrates the SST anomalies of that portion of the Bellingshausen Sea, that area west of the Antarctic Peninsula. Its data peaked in March 2006.http://i35.tinypic.com/kafg5w.jpgFigure 8

Saturday, July 19, 2008

The PDO is calculated using a 5 degree by 5 degree grid of North Pacific SST (North of 20N) anomaly data, where the SST residual and EOFs are determined for each. I don’t have the patience or time to run through all those calculations. In an attempt to illustrate what climatologists were up against when calculating the PDO, I’ve divided the Mid-Latitude (20 to 65N) North Pacific SST and SST anomalies into 10 degrees longitude bands. How someone could even consider that an El Nino like signal (the PDO) was hidden within these data sets is beyond me.

Due to the number of segments, I had to divide the data into two portions: 120E to 180 and 120W to 180. The first graph in each portion is SST. The second is SST anomaly.

One of the curves, (120 to 130E), the one farthest east of those I plotted, clearly indicated an El Nino-like oscillation, so I provided comparative graphs with NINO3.4.

Since I’ve been on an SST kick recently, I decided to download their SST reconstructions that were relatively short term, no longer than 1,000 years, but at least 250 years. I excluded one data set due to the limited number of data points and the sporadic spacing of those readings.

The surprise: There was no hockey stick. Not one. All of the data sets appeared to reflect the real world.

In the following, I provided titles, data citations, links to the data and, where separate, links to the descriptions. For the Indo-Pacific Warm Pool, I also provided ERSST data as a reference to current SST, Figure 4. And for the North Atlantic, since the temperature swings appeared too large, I also provided a comparison to ERSST data, Figure 7. Other than that, the graphs will speak for themselves.

In Figure 3, I shifted the graph scale to cut off much of the spike at 1463 to emphasize the other data. Figure 4 is ERSST.v2 data for the Pacific Warm Pool from 1854 to 2007 that I provided as a reference.http://i34.tinypic.com/2wg7hxy.jpgFigure 3 - Indo-Pacific Warm Pool SST Reconstruction (1004 to 1840) Scale Reduced

Comment Policy, SST Posts, and Notes

Comments that are political in nature or that have nothing to do with the post will be deleted.####The Smith and Reynolds SST Posts DOES NOT LIST ALL SST POSTS. I stopped using ERSST.v2 data for SST when NOAA deleted it from NOMADS early in 2009.

Please use the search feature in the upper left-hand corner of the page for posts on specific subjects.####NOTE: I’ve discovered that some of the links to older posts provide blank pages. While it’s possible to access that post by scrolling through the history, that’s time consuming. There’s a quick fix for the problem, so if you run into an absent post, please advise me. Thanks.####If you use the graphs, please cite or link to the address of the blog post or this website.